234 



PNEUMATICS. 



the current produced ; or, the oppressive heat of half- 

 story bedrooms may he similarly avoided, by creating 

 a current of air between the roof and the plastering 

 {Fig'. 198). Two modes may be adopted, as repre- 

 sented on each side of the figure. 



Fig. 198. 



Mode of Ventilating- half-story Bed- 



